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Biomedical subjects

J C Thomas

Publications and source records attributed to J C Thomas.

At least 37 records · Page 2Linked to original sources
PubMed2000

Short-term impact of a church-based approach to lifestyle change on cardiovascular risk in African Americans.

While lifestyle modification decreases cardiovascular risk, there are barriers to lifestyle education in usual clinical practice, especially among the medically underserved. To address this gap, "Lighten Up," a church-based lifestyle program was developed in collaboration with the local African-American Christian community. Lighten Up includes a baseline health assessment (week 1), eight educational sessions (weeks 2-9) combining study of scripture and a health message, a short-term health check (week 10) and a long-term health check (week 52). Baseline and 10 week risk factor data have been obtained in 133 African Americans from eight sites (83% women) and form the basis of this report. At baseline, 76% of participants had two or more modifiable risk factors (overweight, hypertension, borderline high cholesterol, or diabetes). The entire group had significant short-term reductions in weight (-2.3 pounds, P<.01), mean blood pressure (BP, -2.1 mm Hg, P<.05), and triglycerides (-11 mg/dl, P<.05). Risk factor improvement was greater among the 60 subjects who attended 75% or more of the educational sessions. In this group, weight fell 2.9+/-0.6 pounds (mean +/- SEM; P<.01), mean BP declined 3.8+/-1.2 mm Hg (P<.01), total cholesterol was lowered 6+/-4 mg/ dl (P = .12), and triglycerides were reduced 17+/-9 mg/dl (P = .05). Lighten Up is reaching a group with multiple cardiovascular risk factors that is not optimally managed by existing healthcare resources. Of the 133 participants, 70% attended half or more of the sessions, and several components of the risk factor cluster were favorably affected.

Black or African American↗
PubMed1999

Longitudinal evaluation of serovar-specific immunity to Neisseria gonorrhoeae.

The serovars of Neisseria gonorrhoeae that are predominant in a community change over time, a phenomenon that may be due to the development of immunity to repeat infection with the same serovar. This study evaluated the epidemiologic evidence for serovar-specific immunity to N. gonorrhoeae. During a 17-month period in 1992-1994, all clients of a sexually transmitted disease clinic in rural North Carolina underwent genital culture for N. gonorrhoeae. Gonococcal isolates were serotyped according to standard methods. Odds ratios for repeat infection with the same serovar versus any different serovar were calculated on the basis of the distribution of serovars in the community at the time of reinfection. Of 2,838 patients, 608 (21.4%; 427 males and 181 females) were found to be infected with N. gonorrhoeae at the initial visit. Ninety patients (14.8% of the 608) had a total of 112 repeat gonococcal infections. Repeat infection with the same serovar occurred slightly more often than would be expected based on the serovars prevalent in the community at the time of reinfection, though the result was marginally nonsignificant (odds ratio = 1.5, 95% confidence interval 1.0-2.4; p = 0.05). Choosing partners within a sexual network may increase the likelihood of repeat exposure to the same serovar of N. gonorrhoeae. Gonococcal infection did not induce evident immunity to reinfection with the same serovar.

Adolescent↗
PubMed1999

Characterization of a phycoerythrin without alpha-subunits from a unicellular red alga.

We describe here the spectral and biochemical properties of a novel biliprotein belonging to the phycoerythrin family, purified from the phycobilisome of a unicellular red alga, Rhodella reticulata strain R6. This biliprotein is assembled from a unique beta-type subunit, chloroplast-encoded, whose hexameric or dodecameric aggregates are stabilized by unusually large linkers (87 and 60 kDa) encoded by the nuclear genome. Although each beta-type subunit bears two phycoerythrobilins and one phycocyanobilin per chain, the linker polypeptides are non-chromophorylated. The apoprotein of the beta-subunit of the R. reticulata R6 phycoerythrin is specified by a monocistronic rpeB chloroplast gene that is split into three exons. We discuss the relationships between R6 beta-phycoerythrin and the previously published polypeptide sequences, the structural consequences due to the absence of an alpha-subunit, and its evolutionary implications.

Amino Acid Sequence↗
PubMed1999

The social ecology of syphilis.

Factors affecting the transmission of syphilis can be categorized into those acting at the level of individuals (e.g., number of sex partners) and others at the level of the sociophysical environment (e.g., availability of treatment services for curable infections). In a prior study, we identified several sociophysical factors correlated with the ten-year mean syphilis rate in a regression analysis of United States counties. In the present study we used qualitative methods to investigate additional aspects of some factors in the regression, as well as to identify entirely new factors. Twelve counties with populations less than 100,000 and ten-year mean syphilis rates that were greater or less than expected by the regression model were selected for a three to five day visit. The case study protocol included observations, unstructured interviews with care providers and county residents, and a standardized questionnaire completed by state and local sexually transmitted disease control personnel pertaining to characteristics and practices of the local health department. Comparisons of the field notes and questionnaires revealed patterns of factors of the sociophysical environment that potentially affect county syphilis rates. These included access to the health department STD clinic, race relations, employment opportunities for minorities, interagency coordination, STD outreach activities, the social acceptability of discussing STDs, and intercommunity dynamics. In addition we noted the disproportionate influence of particular individuals on these factors. Some of the factors identified are readily quantifiable and could enhance the predictive power of multivariable models of county syphilis rates. The hypotheses generated by this study may also lead to a better measurement and understanding of potentially important environmental determinants of community syphilis rates, and the development of new or enhanced prevention strategies.

Black or African American↗
PubMed1999

Things ain't what they ought to be: social forces underlying racial disparities in rates of sexually transmitted diseases in a rural North Carolina county.

Social forces shaping a region can also affect behaviors that facilitate the transmission of sexually transmitted diseases (STDs), including HIV. We sought to understand the social forces underlying high rates of infection, particularly among blacks, in a rural county of North Carolina in which 40% of the county is black. In the context of ongoing research on STDs we collected information from archival data on the county since the 1940s and interviewed local residents knowledgeable about the county's history. We present local data in the context of national economic and demographic trends. Successive changes in the national economy and farming policies disproportionately affected black farmers. A rural ghetto formed when poor blacks left their farms to seek work in the central town of the county. Segregationist housing policies and race-based differentials in employment opportunities exacerbated the concentration of poverty. Migration to northern industrial cities, predominantly by skilled black men, decreased the social capital of the community and lowered the ratio of men to women. Poverty, income disparity, social capital and the ratio of men to women can all affect the behaviors that facilitate transmission of STDs. Knowledge of social forces and their effects is critical for designing and evaluating interventions to prevent STDs and to decrease extreme racial disparities in rates of disease.

Adult↗
PubMed1999

Molecular typing of Neisseria gonorrhoeae causing repeated infections: evolution of porin during passage within a community.

Thirty-three Neisseria gonorrhoeae isolates from 15 persons infected multiple times with the same serovar were compared using por gene sequencing, opa-typing, and arbitrarily primed-polymerase chain reaction. All three molecular techniques were more discriminatory than serotyping and identified differences between some isolates belonging to the same serovar. Although there were differences among Por sequences within some serovars, 10 of 15 subjects became reinfected with gonococci expressing identical Por proteins. Sequence analysis of por genes revealed evidence of horizontal genetic exchange and point mutations in potential surface-exposed regions during passage in the community.

Amino Acid Sequence↗
PubMed1999

Self-reported sexual activity and condom use among symptomatic clients attending STD clinics.

BACKGROUND AND OBJECTIVES: A cross-sectional survey of sexually transmitted disease (STD) patients assessed sexual activity and condom use during the time between STD symptom onset and clinic attendance. STUDY DESIGN: Patients were asked to report sexual activity and condom use while STD symptoms were present. Medical records were abstracted for diagnoses. RESULTS: The study population (n = 3025) was predominately African American (75.3%) and male (63.5%), with a mean age of 28.1 years. Sexual activity while experiencing STD symptoms was reported by 39.7% of 2,508 symptomatic patients, 17.2% of whom reported always using a condom. Logistic regression models identified the significant independent determinants of sexual intercourse while symptomatic were duration of symptoms before clinic visit [0-7 days versus 8 or more days, OR = 5.9]; race [African American versus other races (primarily Hispanics), OR = 2.1]; and gender [men versus women, OR = 1.5]. Older age [> or = 30 years versus 18-29 years, OR = 1.5] and higher education attainment [> or = high school versus > high school, OR = 1.5] were the significant factors associated with reporting always using a condom. CONCLUSION: These data suggest patient groups with behaviors likely to enhance STD transmission could be targeted for educational messages.

Adult↗
PubMed1999

Chlamydia trachomatis infection in a rural population: the importance of screening men.

This prospective observational cohort study describes the demographics, risk of re-infection, and geographical distribution of chlamydia infections in a rural North Carolina county. Data were collected between 1 November 1992 and 21 January 1994 from private physician reports and from screening patients at the county health department STD clinic. The overall chlamydia rate in the county was 563 cases per 100,000 person-years. Rates were highest among women, 15-19-year-olds and non-whites (662, 3982 and 1272 cases per 100,000 person-years, respectively). The 6-month cumulative incidence of re-infection was 10%. Geographic mapping of case rates showed contiguity among high-risk block groups. The rate in men, 449 cases per 100,000 person-years, was higher than expected. Issues concerning the development of screening programmes for men are discussed.

Adolescent↗
PubMed1999

An epidemiological evaluation of the use of microbiological tools for identifying gonorrhoea infection networks.

We aimed to assess the utility of various techniques for identifying gonorrhoea infection networks. All residents of a non-metropolitan North Carolina county visiting a sexually transmitted disease (STD) clinic during a 17-month period were screened for gonorrhoea. Infection networks were estimated by serovar type combined with antibiotic resistance, arbitrarily primed polymerase chain reaction (AP-PCR), or temporal clustering. The residential addresses of infected patients were geocoded and mapped. Among 2 serovar types, the presence of distinguishing characteristics of a network, based on questionnaire data, was assessed with prevalence ratios and 95% confidence intervals (CIs) relative to those not in the network. Twenty-five serovar types were identified among 759 gonorrhoea infections. In one serovar, the networks further delineated by temporal clusters correlated with particular AP-PCR types. In most instances, however, different typing techniques painted different network pictures. No refined serovar network stood out as having a particular set of characteristics that could be used to shape intervention. Teasing out an individual infection network with unique characteristics will require the development and use of other microbiological tools.

Adult↗
PubMed1999

What's driving an epidemic? The spread of syphilis along an interstate highway in rural North Carolina.

OBJECTIVES: The purpose of this study was to determine whether county syphilis rates were increased along Interstate Highway 95 (I-95) in North Carolina during a recent epidemic. METHODS: Ecological data on syphilis cases demographic data, highway data, and drug activity data were used to conduct a cross-sectional and longitudinal study of North Carolina countries from 1985 to 1994. Crude and adjusted incidence rate ratios (IRRs) were determined by means of standard and longitudinal Poisson regression models adjusted for sociodemographic factors and drug use. RESULTS: Ten-year syphilis rates in I-95 counties greatly exceeded rates in non-I-95 counties (38 vs 16 cases per 100,000 persons) and remained higher after adjustment for race, age, sex, poverty, large cities, and drug activity (adjusted IRR = 2.05, 95% confidence interval [CI] = 1.84, 2.28). Syphilis rates were stable until 1989, when rates increased sharply in I-95 counties but remained stable in non-I-95 counties. Increased drug activity in I-95 counties preceded the rise in syphilis cases. CONCLUSIONS: A better understanding of the relationship between high-ways and the spread of sexually transmitted diseases may guide future prevention interventions.

Adult↗
PubMed1998

Pedicle screw fixation for arthrodesis of the lumbosacral spine in the elderly. An outcome study.

STUDY DESIGN: An analysis of the outcome and effectiveness of instrumented arthrodesis of the lumbosacral spine in elderly patients conducted using a review of records, assessment of fusion via plain radiographs, and a two-part questionnaire. OBJECTIVE: To ascertain the outcome and efficacy of instrumented arthrodesis of the lumbosacral spine in patients 60 years of age and older. BACKGROUND DATA: From 1987 to 1991, 38 patients of at least 60 years of age underwent instrumented arthrodesis of the lumbosacral spine using the Wiltse or Selby pedicle screw fixation system (Advanced Spine Fixation Systems, Inc., Irvine, CA). Patients were considered for surgery only after attempts at conservative management, including physical therapy, medication, injection blocks, and home exercises, had proven unsuccessful. METHODS: Follow-up examinations were performed 3 months, 6 months, 1 year, and 2 years after surgery. Fusion was assessed using plain radiographs, including flexion-extension films. Inpatient and outpatient records were reviewed, and a two-part questionnaire was used to establish the effect of surgery on function and lifestyle. Thirty patients responded to the questionnaire. Follow-up observation of the patients ranged from 25 to 56 months. The mean age was 73.8 years (range, 60-90 years). RESULTS: The mean co-morbidity was 1.7. Based on the authors' method of evaluation of fusion, the fusion rate was 92%. Fifty-seven percent of the patients reported excellent or good results, 26% reported fair results, and 17% reported poor results. Functional gains of 50% or more were reported by 71% of the respondents. Female patients had significantly more complications than male patients, but reported comparable outcomes. CONCLUSION: Despite the increase in age, co-morbidity, and associated risk of perioperative complications inherent in this population, an outcome comparable with that of younger patients is reported.

Aged↗
PubMed1998

The indole alkaloid tryptamine impairs reproduction in Drosophila melanogaster.

The plant-produced indole alkaloid tryptamine is one of a large array of neuroactive substances that may affect insect behavior, development, and physiology. We tested the role of tryptamine on insect reproduction using the fruit fly, Drosophila melanogaster (Meigen), as a model system. Measurements were made of reproductive success, oviposition rate, and preadult survival of insects on artificial diets containing tryptamine, its precursor tryptophan, as well as glycine and serotonin (5-hydroxytryptamine). Drosophila reproduction was reduced to 15% of controls when adult insects mated and the young were allowed to develop on medium containing 75 mM tryptamine. Tryptamine-induced depression in reproductive success was due to decreased oviposition rate and preadult survival. Serotonin, but not tryptophan or glycine, also reduced oviposition rate. Preference tests indicated that tryptamine may act as an antiattractant or antifeedant in this species. The accumulation of the indole alkaloid tryptamine in plants may provide a mechanism for reducing insect reproduction, which is potentially useful in protecting crop plants.

Animals↗
PubMed1998

Prevalence of HIV-associated periodontitis and chronic periodontitis in a southeastern US study group.

OBJECTIVES: This study estimates factors associated with the prevalence of HIV-associated periodontal diseases (HIV-P) and the severity and extent of periodontitis in HIV-infected adults from North Carolina (NC). METHODS: Data are derived from a cross-sectional study of HIV-infected adults (total n = 326, dentate n = 316) treated at the University of North Carolina Hospitals. Outcomes were a diagnosis of HIV-P and measures of probing pocket depth (PPD), recession (REC), and clinical attachment level (CAL). Immunosuppression was measured by peripheral blood CD4+ cells/mm3. RESULTS: In addition to persons with HIV (non-AIDS), this study included 10 percent of the AIDS cases in North Carolina. Median age was 37 years (range = 19-67); 78 percent were male and 60 percent were black. Sixty-two percent of persons had a probing pocket depth > or = 5 mm; 46% had recession > or = 3 mm, and 66 percent had attachment level > or = 5 mm in one or more sites. Cases of HIV-P (n = 15) were rare. Persons taking HIV-antiretroviral medication were one-fifth (OR = 0.20; 95% CI = 0.07, 0.63) as likely to have HIV-P as those not taking those medications, controlling for CD4+ cell counts. CONCLUSIONS: HIV-infected persons in this study group from North Carolina exhibited severe and extensive measures of adult periodontitis. A small proportion experienced a severe form of HIV-P, which was attenuated by antiretroviral therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Reproductive decisions of women at risk for acquiring HIV infection.

Approximately 1 to 1.5 million people in the United States are infected with HIV. The incidence of HIV is increasing among women and children. Little information exists regarding the determinants of reproductive decisions of women at risk of HIV infection. This study investigated the correlates of reproductive decisions using data from the National AIDS Demonstration and Research Projects funded by the National Institutes on Drug Abuse. Subjects for this study were 1,921 women. HIV serostatus, AIDS knowledge, and perceived risk for getting AIDS were not associated with the reproductive decisions. Major correlates of reproductive decisions were age, ethnicity, and the number of children living with the women. Pregnancy, 6 months after the baseline interview, was associated with intention to become pregnant at baseline. In addition age and education level were significant predictors of self-reported pregnancy at follow-up.

Adult↗
PubMed1997

Quantitative flow cytometric detection of specific microorganisms in soil samples using rRNA targeted fluorescent probes and ethidium bromide.

Specific detection and accurate enumeration of microorganisms in the environment have been hampered by the lack of suitable techniques. A three-parameter flow cytometric method (FCM) was developed to detect quantitatively Sphingomonas sp. strain 107 inoculated into soil samples. By combining light scattering profiles (i.e., morphological properties), ethidium bromide (EtBr) influx (i.e., wall permeability), and fluorescence in situ hybridization against the 16S rRNA (i.e., detection specificity), we could accurately discriminate the bacterium of interest from the indigenous microflora and soil debris. EtBr was used, first, to determine the optimal cell wall permeabilization treatment to allow oligonucleotide probes to enter the bacterial cells and, second, to achieve clear discrimination of fixed cells from debris in soil samples. This method allowed effective qualitative and quantitative analysis by fluorescence in situ hybridization. The results showed that the detection threshold by FCM was 3 x 10(4) cells/g of dry soil. Cell counts deduced from FCM analysis were similar to those obtained by the colony forming unit assay when soils contained fewer than 3 x 106 cells/g dry soil. This method should be useful for either quantitative monitoring of microorganisms inoculated in contaminated soil samples during bioremediation or detecting known bacterial strains in environmental samples.

Cell Separation↗
PubMed1997

Rapid method for detecting Desulfitobacterium frappieri strain PCP-1 in soil by the polymerase chain reaction.

A rapid method was developed for detecting in soil Desulfitobacterium frappieri strain PCP-1, an anaerobic gram-positive bacterium, isolated from a methanogenic consortium degrading pentachlorophenol. The method involved the establishment of a protocol for extracting total DNA from soil with the least contamination, and the use of the polymerase chain reaction (PCR) to detect strain PCP-1 with primers targeted with PCP-1 16S rRNA. To optimize the DNA extraction conditions, a glass mill homogenizer and a low-salt buffer containing polyvinylpolypyrrolidone were used on a black soil rich in organic matter. Recovered DNA was further purified with phenol/chloroform extractions, ammonium acetate precipitation and a G200 Sephadex gel-filtration column. DNA was extracted from soil supplemented with different concentrations of PCP-1 cells. Detection of PCP-1 was by PCR. The limit of detection was 800 added PCP-1 cells/g dry soil. This level of detection was achieved when the T4 gene-32 protein and 1 microgram soil DNA were added to the PCR mixture followed by a nested PCR. This method is quick, sensitive, and can process several samples at the same time.

Bacteria, Anaerobic↗